• Corrosion Science and Technology
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• v.22 no.6
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• pp.419-428
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• 2023

Seawater has been used to cool devices in nuclear power plants. However, the pipes used to transport seawater are vulnerable to corrosion; hence, the inner side of pipelines is coated with an epoxy layer as prevention. Upon coating damage, the pipe becomes exposed, and corrosion progresses. The major cause is widely known as cavitation corrosion, causing the degradation of mechanical properties. In this study, corroded specimens were prepared using cavitation and immersion methods to clarify the degradation trend of mechanical properties with corrosion. Three different types of epoxy coatings were used, and accelerated cavitation procedures were composed of amplitudes of 15 ㎛, 50 ㎛, and 85 ㎛ for 2 h, 4 h, and 6 h. The immersion periods were 3 and 6 weeks. We conducted instrumented indentation tests on all degradation samples to measure mechanical properties. The results showed that higher cavitation amplitudes and longer cavitation or immersion times led to more degradation in the samples, which, in turn, decreased the yield strength. Of the three samples, the C coating had the highest resistance to cavitation and immersion degradation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.4
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• pp.48-54
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• 2024

NPP (Nuclear power plant) structures have been constructed near to the sea shore line for cooling water and exposed to steel corrosion due to chloride attack. Regarding NPP structures built in the UAE, chloride transport may be more rapid than those in the other regions since the temperature near to the coast is high. In this study, concrete samples with 5,000psi (35MPa) design strength grade were manufactured with the materials and mix proportions, which were the same as used in the UAE NPP structures, then chloride diffusion coefficients were evaluated considering temperature and curing age. The compressive strength and the diffusion coefficient were evaluated and analyzed for the samples with 28 and 91 curing days. In addition, chloride diffusion tests for 91-day-cured condition were carried out in the range of 20℃ to 50℃. The activation energy was obtained through converting the temperature slope to a logarithmic function and it was compared with the previous studies. The proposed activation energy can be useful for a reasonable durability design by using actual temperature-dependent chloride diffusion coefficient.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.1
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• pp.63-75
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• 2012

This paper gives some basic requirements and preferences of various geological environmental conditions for the final deep geological repository of spent nuclear fuel (SNF). This study also indicates how the requirements and preferences are to be considered prior to the selection of sites for a site investigation as well as the final disposal in Korea. The results of the study are based on the knowledge and experience from the IAEA and NEA/OECD as well as the advanced countries in SNF disposal project. This study discusses and suggests preliminary guideline of the disposal requirements including geological, mechanical, thermal, hydrogeological, chemical and transport properties of host rock with long term geological stabilities which influence the functions of a multi-barrier disposal system. To apply and determine whether requirements and preferences for a given parameter are satisfied at different stages during a site selection and suitability assessment of a final disposal site, the quantitative criteria in each area should be formulated with credibility through relevant research and development efforts for the deep geological environment during the site screening and selection processes as well as specific studies such as productions of safety cases and validation studies using a generic underground research laboratory (URL) in Korea.

• Journal of Korean Neurosurgical Society
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• v.29 no.10
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• pp.1309-1315
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• 2000

Objectives : We performed an in vivo experiment to investigate the effect of $^{166}Holmium$ and $^{166}Holmium$-chitosan complex($^{166}Ho$-CHICO) on the normal brain of rats and to determine the sublethal dose of $^{166}Ho$-CHICO. Materials and Methods : $^{166}Ho$ is a beta and gamma ray emitter. $^{166}Ho$-CHICO is a novel radio-pharmaceutical complex with chitosan to facilitate the transport of $^{166}Ho$ obtained from Korea Atomic Energy Research Center(Taejon, Korea). It is in acidic form and becomes gel state at alkaline pH. One hundred and seventy consecutive rats were divided into four groups : $^{166}Ho$ treated(n＝50), $^{166}Ho$-CHICO treated(n＝57), saline treated(n＝5) and chitosan treated(n＝5) groups. $^{166}Ho$ and $^{166}Ho$-CHICO were injected into the rat brain stereotactically with various doses of 0.1mCi/$20{\mu}l$, 0.2mCi/$20{\mu}l$, 0.3mCi/$20{\mu}l$, and 0.4mCi/$20{\mu}l$ using an automated microinjector. Nuclear imaging, histopathological and hematological studies were performed in 10 rats in each group at 1 day, 3days, 7 days, 1 month and 3 months after the injections. Results : An infiltration of inflammatory cells and necrotic changes were noted in $^{166}Ho$ treated group at 1 week after the injection. A wedge-shaped tissue defect due to necrosis, lined with infiltrated glial cells in $^{166}Ho$ treated group and a cystic defect lined with reactive astroglial cells in $^{166}Holmium$-CHICO treated group at 3 months after the injection were observed. $^{166}Ho$ alone without chitosan leaked out and caused necrotic lesion on the cerebral surface but $^{166}Holmium$-CHICO treated group did not show this feature. As the dose of $^{166}Ho$ increased, the mortality rates were also increased. The mortality rate of the $^{166}Holmium$-CHICO group was higher than the $^{166}Ho$ treated group at a dose of 0.4mCi/$20{\mu}l$/300g. There was no detectable radioactivity due to the leakage or extravasation from the injected site of the brain on the scintigraphy performed at 1 hour, 24 hours and 48 hours after the injection. There was also no detectable activity of $^{166}Holmium$-CHICO in other organs including spleen, liver and kidney. Conclusions : $^{166}Ho$-CHICO did not leak out to the critical cortical surface of the brain from the injection site and induced radiation changes of the parenchyma around the injection site without cortical damage. The sublethal dose of $^{166}Ho$-CHICO for the normal brain in rats was determined to be 0.2mCi/$20{\mu}l$/300g.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2_spc
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• pp.317-325
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• 2020

The Korea Radioactive Waste Agency plans to expand the storage capacity of radioactive waste by constructing a radioactive waste inspecting building to solve the problem of the lack of inspection space and drum-handling space in the radioactive waste receipt and storage building for the first-stage disposal facility. In this study, the exposure doses of radiation workers that handle new disposal containers for decommissioning waste in the storage areas of the radioactive waste inspecting building were calculated using the Monte Carlo N-particle transport code. The annual collective dose was calculated as a total of 84.8 man-mSv for 304 new disposal containers and an estimated annual 306 working hours for the radiation work. When the 304 new disposal containers (small/medium type) were stored in the storage areas, it was found that 25 radiation workers should be involved in acceptance/disposal inspection, and the estimated exposure dose per worker was calculated as an average annual value of 3.39 mSv. When the radiation workers handle the small containers in high-radiation dose areas, the small containers should be shielded further by increasing the concrete liner thickness to improve the work efficiency and radiation safety of the radiation workers. The results of this study will be useful in establishing the optimal radiation working conditions for radiation workers using the source term and characteristics of decommissioning waste based on actual measurements.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.5
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• pp.386-391
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• 2010

Introduction: Bone resorption is a unique function of osteoclasts. Osteoclasts are a specialized macrophage polykaryon whose differentiation is regulated principally by macrophage colony-stimulating factors, receptor activator of nuclear factor ${\kappa}B$ ligand (RANK) ligand, osteoprotegerin (OPG), and interleukins (IL). Reflecting the integrin-mediated signals, osteoclasts develop a specialized cytoskeleton that allows it to establish an isolated micro-environment between itself and the bone, wherein matrix degradation occurs by a process involving proton transport. The levels of IL-1, IL-6, OPG, and prostaglandin $E_2$ ($PGE_2$) expression were evaluated to study the correlations between dental implant teeth and the adjacent teeth. Materials and Methods: The exudate of the gingival crevice acquired from dental implants, adjacent teeth, opposite teeth and contralateral teeth of 24 patients. Results: 1. The levels of IL-1, IL-6, OPG and $PGE_2$ expression in dental implant teeth were higher than those of the contralateral teeth. 2. IL-1 revealed a higher expression level in the adjacent teeth than in dental implant teeth. 3. The dental implant teeth and adjacent teeth did not show a remarkable difference in the level of IL-1 expression. 4. All the other cytokines were strongly expressed in the dental implant compared to the adjacent teeth. Conclusion: These results suggest that there might be close correlation between dental implant teeth and adjacent teeth in terms of the expressions of cytokines that affect the development and regulation of osteoclasts.

• Tunnel and Underground Space
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• v.9 no.4
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• pp.306-314
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• 1999

In underground spaces including nuclear waste repository, prediction of air quantity, temperature/humidity and pollutant concentration is utmost important for space construction and management during the normal state as well as for determining the measures in emergency cases such as underground fires. This study aims at developing a model for underground space environment which has capabilities to take into account the effects of autocompression for the natural ventilation head calculation, to find the optimal location and size of fans and regulators, to predict the temperature and humidity by calculating the convective heat transfer coefficient and the sensible and latent heat transfer rates, and to estimate the pollutant levels throughout the network. The temperature/humidity prediction model was applied to a military storage underground space and the relative differences of dry and wet temperatures were 1.5 ~ 2.9% and 0.6 ~ 6.1%, respectively. The convection-based pollutant transport model was applied to two different vehicle tunnels. Coefficients of turbulent diffusion due to the atmospheric turbulence were found to be 9.78 and 17.35$m^2$/s, but measurements of smoke and CO concentrations in a tunnel with high traffic density and under operation of ventilation equipment showed relative differences of 5.88 and 6.62% compared with estimates from the convection-based model. These findings indicate convection is the governing mechanism for pollutant diffusion in most of the tunnel-type spaces.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.1
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• pp.33-40
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• 2011

In the compacted bentonite containing $Ag_2O$, the transport of iodide ion was investigated by Through-diffusion method. It is confirmed that Iodide ion is transported by diffusion process in the compacted bentonite containing $Ag_2O$ as well as in the compacted bentonite without $Ag_2O$. However, the lag-time of iodide ion in the compacted bentonite containing $Ag_2O$ is larger than that in the compacted bentonite without $Ag_2O$. The increase of the lag-time was observed in pure iodide ion solution and also in 0.1M NaCl-iodide ion solution. The apparent diffusion coefficient of iodide ion in the compacted bentonite containing $Ag_2O$ has lower value than that in the compacted bentonite without $Ag_2O$. The effect of $Ag_2O$ on the effective diffusion coefficient was not clearly investigated in the compacted bentonite containing $Ag_2O$ while the values of effective diffusion coefficient of iodide ion in the compacted bentonite without $Ag_2O$ obtained in this study were similar to those in the compacted bentonite reported in the literature.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2
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• pp.179-194
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• 2020

A Bayesian approach was introduced to improve the belief of prior distributions of input parameters for the probabilistic safety assessment of radioactive waste repository. A GoldSim-based module was developed using the Markov chain Monte Carlo algorithm and implemented through GSTSPA (GoldSim Total System Performance Assessment), a GoldSim template for generic/site-specific safety assessment of the radioactive repository system. In this study, sequential Bayesian updating of prior distributions was comprehensively explained and used as a basis to conduct a reliable safety assessment of the repository. The prior distribution to three sequential posterior distributions for several selected parameters associated with nuclide transport in the fractured rock medium was updated with assumed likelihood functions. The process was demonstrated through a probabilistic safety assessment of the conceptual repository for illustrative purposes. Through this study, it was shown that insufficient observed data could enhance the belief of prior distributions for input parameter values commonly available, which are usually uncertain. This is particularly applicable for nuclide behavior in and around the repository system, which typically exhibited a long time span and wide modeling domain.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.1
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• pp.44-51
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• 2012

Calcium ions play an important role in the establishment and maintenance of pregnancy, but molecular and cellular regulatory mechanisms of calcium ion action in the uterine endometrium are not fully understood in pigs. Previously, we have shown that calcium regulatory molecules, transient receptor potential vanilloid type 5 (TRPV6) and calbindin-D9k (S100G), are expressed in the uterine endometrium during the estrous cycle and pregnancy in a pregnancy status- and stage-specific manner, and that estrogen of conceptus origin increases endometrial TRPV6 expression. However, regulation of S100G expression in the uterine endometrium and conceptus expression of S100G has been not determined during early pregnancy. Thus, we investigated regulation of S100G expression by estrogen and interleukin-$1{\beta}$ (IL1B) in the uterine endometrium and conceptus expression of S100G during early pregnancy in pigs. We obtained uterine endometrial tissues from day (D) 12 of the estrous cycle and treated with combinations of steroid hormones, estradiol-$17{\beta}$ ($E_2$) and progesterone ($P_4$), and increasing doses of IL1B. Real-time RT-PCR analysis showed that $E_2$ and IL1B increased S100G mRNA levels in the uterine endometrium, and conceptuses expressed S100G mRNA during early pregnancy, as determined by RT-PCR analysis. To determine if endometrial expression of S100G mRNA during the implantation period was affected by the somatic cell nuclear transfer (SCNT) procedure, we compared S100G mRNA levels in the uterine endometrium from gilts with SCNT-derived conceptuses with those from gilts with conceptuses derived from natural mating on D12 of pregnancy. Real-time RT-PCR analysis showed that levels of S100G mRNA in the uterine endometrium from gilts carrying SCNT-derived conceptuses was significantly lower than those from gilts carrying conceptuses derived from natural mating. These results showed that S100G expression in the uterine endometrium was regulated by estrogen and IL1B of conceptus origin, and affected by the SCNT procedure during early pregnancy. These suggest that conceptus signals regulate S100G, an intracellular calcium transport protein, for the establishment of pregnancy in pigs.